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The Full-Body Backlash

By Nate Silver November 15, 2010 7:32 pmNovember 15, 2010 7:32 pm

8:07 p.m. | Updated

As full-body scanners come into more widespread use in American airports (they will be phased in soon at the three major airports in the New York City metro region), they are also coming under more frequent criticism.

The objections are coming from many different quarters:

Unions representing American Airlines and US Airways, citing concerns about radiation, have asked their pilots to bypass the scanning machines and instead opt for a pat-down.

Bipartisan groups of legislators in New Jersey and Idaho are working to ban the use of such systems in their states.

A California man named John Tyner who wrote about — and videotaped — his experience at San Diego International Airport, in which he claimed to have been threatened with a $10,000 fine for refusing a pat-down even after he decided not to board his flight, received more than 4,000 comments to his blog, the vast majority of them sympathetic.

Another blogger has called for Wednesday, Nov. 24th — among the busiest travel days of the year — to be “national opt-out day,” encouraging people to submit to a pat-down (and to have it done in full view of other passengers) rather than go through the body-scanning machines.

So is there a backlash brewing?

Before we look at what the polls have to say — and at some of the potential problems with them — I should make clear that I’m sympathetic to these arguments. As I’ve written in the past, the risk of airplane-based terrorism is probably overstated, and may obscure more serious threats like that posed by the potential for terrorists to gain access to weapons of mass destruction.
My first experience with the full-body scanners, on a flight back to Kennedy Airport from San Diego last month, was also a negative one. I had assumed that, whatever their other faults, the full-body scanners would at least speed up the process of going through the security line; I supposed I imagined something like this scene from the movie Total Recall, in which passengers literally don’t even have to pause to go through security as their bodies are scanned while they walk toward the departure gate.

Instead, the lines were quite slow — possibly because the machines were coming up with a lot of false positives, myself included. As is my usual practice when passing through airport security, I emptied my pants pockets completely — there wasn’t so much as a stick of gum, a penny, or a taxi receipt in there. But the machine nevertheless insisted that that there was something in the back right-hand pocket of my jeans. When the official from the Transportation Security Administration asked me what I had in my pocket, and I told him that there was absolutely nothing, he then performed a pat-down. I was in a chipper enough mood that I wasn’t inclined to make a scene, but I did ask the T.S.A. official whether it was routine for the machines to see things that weren’t there, to which he declined to respond.

This is not necessarily to suggest that my experience was typical — although perhaps there are some particular issues in San Diego, the same airport at which Mr. Tyner experienced his problems, and perhaps there is something of a learning curve as T.S.A. crews learn how to use the new technologies effectively.

Still, it shifted my overall opinion of the technology from positive to negative. This may be something to keep in mind when reviewing polls on the topic.

The T.S.A. is fond of citing polls which suggest that about 75 or 80 percent of air travelers approve of the new machines. There are a couple of issues having to do with the timing of these surveys, however. Most of them were conducted in January, immediately after the failed attempt last Christmas day by a Nigerian man, who had concealed explosives in his underwear, to blow up a plane travelling from Amsterdam to Detroit — during which time concern about air travel security would naturally have been quite elevated.

In addition, the surveys were conducted at a time when virtually no Americans would have had experiences with the full-body scanners, which had not yet been installed in any American airports at that time. Again, I have no way of knowing whether my experience at San Diego was at all typical. But if so, I would imagine that other people might have their opinions shifted after actually having encountered the machines.

In general, surveying Americans on issues related to airport security is problematic because most Americans fly rarely, if ever. A Gallup poll conducted in 2008, for instance, found that just 44 percent of Americans reported having flown at least once in the past year. In fact, this is probably an overestimate. The Gallup poll reported that American adults had taken an average of 1.7 round trips by airplane in the past year. Statistics compiled by the Department of Transportation, however, found a total of about 800 million passengers boarded flights offered by U.S.-based carriers in 2008. Since a typical round-trip consists of either 2 or 4 flights (depending on whether there is a layover or not; a round-trip might also involve as many as 6 or 8 flights when there are multiple layovers), this implies that there were something on the order of 250 million round trips made by airplane in 2008, which would be fewer than one per American, rather than the 1.7 trips that the Gallup poll found. My guess is that the fraction of Americans who travel by plane each year is in fact probably not more than about 1 in 3.

In addition, these flights are concentrated among relatively few people. A study by the market-research firm Arbitron found, for instance, that frequent fliers — those who take 4 or more round trips per year — account for the 57 percent majority of all air travel, even though they make up just 18 percent of air travelers and something like 7 percent of the overall American population.

At least one past survey has identified differences in perceptions about airport security procedures between frequent and occasional fliers. This was a 2007 Gallup poll, which found that while just 26 percent of occasional travels were dissatisfied with airport security, the level rose to 37 percent among those who fly more frequently.

What I think we need to know then, is how those who have actually traveled through an airport that uses the full-body scanners feel about them — particularly if they’re people who fly frequently and are therefore going to bear the burden of any inconvenience, embarrassment, invasion of privacy or health risk brought on by the new technology.

My guess is that a majority of such passengers will still approve of them: Americans are willing to tolerate a great number of things at the airport that they would never stand for in other parts of their lives. (Imagine, for instance, if you had to pass through a metal detector on the way into the shopping mall, or were diverted for 15 minutes through a security checkpoint every time that you wanted to drive on the Interstate.)

But the holiday travel period — when nerves are always frayed and the weather is often at its worst — will be a significant test of the new system. I would advise passengers to get to the airport early, particularly if they are flying out of airports, like San Diego, where the systems have been installed very recently.

Update: Just as we were posting this item, a new poll came in from CBS News showing 81 percent of Americans supporting the full body scans. So, it does not appear that the high levels of support were an artifact of the timing of the previous surveys, most of which had been conducted shortly after the Christmas Day bombing attempt.

Nevertheless, I would guess that only somewhere between 1 and 5 percent of Americans have so far traveled through a security line where such machines were in use; it will probably take some time before we know where public opinion settles in on this topic.

Another issue is that most of these surveys are asking about the full-body machines in a vacuum. I’d be curious to see what the results were if respondents were asked to pick between full-body machines and traditional metal detectors.

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This is an archive of posts from FiveThirtyEight, a blog founded by Nate Silver in 2008 and devoted to rigorous, data-driven analysis of politics, polling, public affairs, sports, economics, science and culture, from August 2010 through July 2013.